ACJC_H1_CHEM_P2 Prelim

1 Centre Number Index Number Name and Class ANGLO-CHINESE JUNIOR COLLEGE PRELIMINARY EXAMINATIONS Advanced Level CHEMISTRY 8872/02 Higher 1 Paper 2 Structured & Free Response 24th August 2009 2 hour Candidates answer on the Question Paper & Writing Paper Additional Materials: Data Booklet Writing Paper String READ THESE INSTRUCTIONS FIRST Write your name, Centre number and index number on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions in Section A & answer 2 out of 3 questions in Section B A Data Booklet is provided. The number of marks is given in brackets [ ] at the end of each question or part question. At the end of the examination, fasten all your work securely together including the cover page. For Examiner's Use Question no. Marks 1 2 3 Section A 4 Section B (2 out of 3) Total This document consists of 10 printed pages. ACJC 2009 8872/02/Aug/09 Preliminary Examination

2 Section A Answer all questions in the spaces provided on the question paper. 1 Carbonyl chloride, COCl 2 (structure as shown below), exists as a toxic gas which reacts rapidly with water to evolve two different acidic gases. C O ClCl (a) (i) The reaction of carbonyl chloride with water is found to proceed via the reaction pathway as shown below: C O ClCl Name the reaction that has occurred to produce the intermediate A. [1] (b) An unknown amount of carbonyl chloride was reacted with water (in excess). COCl 2 + H2O → 2HCl + CO2 The two acidic gases required 25.0cm 3 of 0.100mol dm -3 o f N a O H f o r complete neutralization. (i) Calculate the amount of NaOH that has reacted. [1] (ii) Given that complete neutralization occurs for the two gases, write two equations to show the reactions of NaOH with HCl and NaOH with CO 2 respectively. [2] HCl + CO2 Intermediate A Intermediate B C OH HO Cl Cl C O ClHO ACJC 2009 8872/02/Aug/09 Preliminary Examination

3 (iii) Using your answers in (ii), calculate the volume of HCl evolved at room temperature and pressure given that 1 mol of a gas occupies a volume of 24 dm3 under room temperature and pressure. [1] (c) (i) Chlorine has an oxidation state of -1 in HCl. State the oxidation states of chlorin